Automated on-line separation–preconcentration system for inductively coupled plasma atomic emission spectrometry and its application to mercury determination

Abstract

An automated separation–preconcentration system coupled to an inductively coupled plasma atomic emission spectrometer is described. The preconcentration step is performed on a chelating resin microcolumn [silica gel functionalized with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide] placed in the injection valve of a simple flow manifold. The system was applied to the determination of mercury in sea-water and biological samples. The optimum experimental conditions were evaluated for the continuous preconcentration of mercury, the direct generation of mercury vapour and the final determination of this element by ICP-AES. The proposed method has a linear calibration range from 2 to at least 1000 ng ml–1 of mercury, with a detection limit of 1 ng ml–1 (S/N=3) and a throughput of 40 samples h–1, for a 6 ml sample volume. The accuracy of the method was examined by the analysis of certified reference materials and by determining the analyte content in spiked environmental waters. The results show sufficiently high recoveries.